From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758472AbYDALVo (ORCPT ); Tue, 1 Apr 2008 07:21:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756423AbYDALVh (ORCPT ); Tue, 1 Apr 2008 07:21:37 -0400 Received: from smtp.nokia.com ([192.100.105.134]:39252 "EHLO mgw-mx09.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756035AbYDALVg (ORCPT ); Tue, 1 Apr 2008 07:21:36 -0400 Message-ID: <47F219B0.6020109@nokia.com> Date: Tue, 01 Apr 2008 14:17:04 +0300 From: Artem Bityutskiy Reply-To: Artem.Bityutskiy@nokia.com Organization: Nokia OYJ User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: =?UTF-8?B?SsO2cm4gRW5nZWw=?= CC: Artem Bityutskiy , Adrian Hunter , Jan Engelhardt , LKML , joern@lazybastard.org Subject: Re: UBIFS vs Logfs (was [RFC PATCH] UBIFS - new flash file system) References: <1206629746-4298-1-git-send-email-Artem.Bityutskiy@nokia.com> <47F0DD49.7010302@nokia.com> <20080331132047.GA31660@logfs.org> <47F1C78D.2050300@yandex.ru> <47F1CE9D.4080709@nokia.com> <20080401092548.GC7465@logfs.org> <47F202CD.4000804@yandex.ru> <20080401105104.GE7465@logfs.org> In-Reply-To: <20080401105104.GE7465@logfs.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-OriginalArrivalTime: 01 Apr 2008 11:20:56.0519 (UTC) FILETIME=[74700D70:01C893EA] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jörn Engel wrote: > Fair enough. > > The obvious downside of all this is depending on UBI, which has a linear > scan. My goal was to avoid the linear scan completely. It is a harder > goal and I haven't reached it yet. Imo it is reachable and I will > continue going in that direction. Yes, it was our core design decision. One of the reasons, we were not sure this is technically possible to do on bare flashes. I mean, it just looked so complex to have all in one, so we figured that was a good split, where you can cut on big work on two smaller separate ones. The benefit of this is obvious - we have created a complete system, which is not perfect though and have scalability issues. Our point is that UBI is scalable enough for the time being. I wrote some documentation about this in UBI FAQ and UBIFS FAQ: http://www.linux-mtd.infradead.org/doc/ubifs.html#L_scalability We can now improve scalability of UBI without affecting UBIFS - it has some potential. And we may develop UBI2 which would be more much more scalable, but this is a big project and we are not planning to do this so far. Others could do. So in other words, using UBI allowed us to get a finished system faster. I meets our's and many other people's requirements, although it has issues if you try to use it on really huge flashes, like 64GiB. That's a drawback. But the good thing is that this would require re-working UBI layer, without complete re-working of UBIFS. > You picked the route of using UBI, which makes a lot of stuff easier. > It is a fair approach and I don't mind you taking it. It has drawbacks, > but so has everything else. Agree. -- Best Regards, Artem Bityutskiy (Артём Битюцкий)